Cold starting devices

Abstract

An internal combustion engine cold start device has an air valve which co-operates with a valve seat to vary the cross-sectional area of an auxiliary air supply passage upstream of a plug valve in the passage. The air valve is urged towards the valve seat by coil spring. A fuel metering orifice communicates with the passage between the two valves. The plug valve has a profiled valve member which is linked to a profiled needle which projects into the fuel metering orifice, the needle and the plug valve member being guided for rectilinear movement together along parallel paths to respectively throttle the passage and vary the area of the metering orifice. A coil spring opposes rectilinear movement of the plug valve member and the needle to reduce flow through the passage and the orifice respectivey. A thermostatically controlled movable stop co-operates with the linkage which links the plug valve member and the needle so as to limit the permitted movement of the plug valve member and the needle together against the action of the coil spring and to increase that permitted movement as the temperature of the engine increases. In one embodiment the air valve and the plug valve are coaxial, the air valve being annular and being guided by a rod which carries the plug valve member. In another embodiment the air valve is carried by a plunger which slides in a through bore in the body of the device, the through bore being parallel to the plug valve path and communicating with the passage downstream of the plug valve.

I claim: 
     
       1. A cold starting device for an internal combustion engine, the cold starting device comprising an auxiliary air supply passage; a first valve member within said auxiliary air supply passage; first biasing means which bias said valve member into an open position at least when the cold starting device is in use, the valve member being arranged so as to tend to be moved when the device is installed on an internal combustion engine by engine suction into a closed position in which it minimizes the flow of air past it to the engine; guide means which guide said valve member for rectilinear movement within said auxiliary air supply passage between said open and closed positions; a fuel metering orifice; conduit means which place said fuel metering orifice in communication with the auxiliary air supply passage upstream of said closed position of said valve member so that metered quantities of fuel can be drawn therethrough into said auxiliary air supply passage by engine suction when said valve member is in the open position; and a thermostatically controlled movable stop for limiting the movement of the valve member towards said closed position, the position of said stop being related to engine temperature so that movement of said valve member is minimized by said stop when the engine is cold and is allowed to increase as the engine warms up towards normal operating temperature whereby movement of said valve member to said closed position is permitted, wherein the improvement comprises a second valve member; a cooperating valve seat positioned within said auxiliary air supply passage upstream of that part of the auxiliary air supply passage with which the fuel metering orifice communicates; second biasing means which urge the second valve member into engagement with said valve seat; the arrangement being such that the second valve member can be seated on said valve seat during the engine cranking period and moved by the depression which is established within said part of the auxiliary air supply passage against the action of the biasing load and away from said valve seat when the engine commences to run under its own power so that the constitution of fuel/air mixture supplied to the engine during starting from cold and warming up of the engine is changed firstly at the termination of the cranking period as well as being further changed progressively once the engine is running under its own power and until it has attained its normal operating temperature. 
     
     
       2. A cold starting device as claimed in claim 1, wherein said first biassing means comprises a coil spring. 
     
     
       3. A cold starting device according to claim 1, wherein said second valve member is guided for rectilinear movement towards and away from said co-operating valve seat and said second biassing means comprise a coil spring. 
     
     
       4. A cold starting device according to claim 1, wherein the first valve member is a plug valve member which co-operates with an orifice in the auxiliary air supply passage to control the flow of fuel/air mixture through the said orifice to the engine, the plug valve member being profiled so that the flow of fuel/air mixture past it to the engine is metered in accordance with engine temperature. 
     
     
       5. A cold starting device according to claim 4, wherein the profiled plug valve member is fixed to a rod, and said guide means comprise a guide sleeve which is supported within the auxiliary air supply passage, the rod being in sliding engagement within the guide sleeve by which it is guided for rectilinear movement. 
     
     
       6. A cold starting device according to claim 5, including a profiled needle; coupling means for coupling said profiled needle to the valve member and further guide means for guiding said profiled needle for rectilinear movement with movement of said valve member, the profiled needle projecting into the fuel metering orifice so that the effective area of the fuel metering orifice is varied with movement of the valve member, wherein said first biassing means comprise a coil spring which urges the profiled needle into the position in which the effective cross-sectional area of the fuel metering orifice is at its greatest. 
     
     
       7. A cold starting device according to claim 6, wherein an arm is carried by the rod, from which it extends laterally, and is fixed to the needle so that the profiled needle and the rod are parallel, the arm being associated with the thermostatically controlled movable stop so that movement of the plug valve member towards said closed position is limited by the movable stop. 
     
     
       8. A cold starting device according to claim 1, including an expansible capsule by which the position of the thermostatically controlled movable stop is controlled, the expansible capsule being arranged to expand with increase in engine temperature; and a pivoted beam which carries said stop; wherein the expansible capsule acts to permit rotation of the beam about its pivot support, due to the action of resilient means, as the engine temperature increases. 
     
     
       9. A cold starting device according to claim 8 wherein the expansible capsule acts to hold the valve member in its closed position when the engine has attained its normal operating temperature. 
     
     
       10. A cold starting device according to claim 5 wherein said second valve member is annular and is guided for rectilinear sliding movement by said rod which is a sliding fit within its central aperture. 
     
     
       11. A cold starting device as claimed in claim 1, wherein said second valve member is connected to a movable wall so as to move with movement of the movable wall, the surface of the movable wall remote from said other valve member being exposed to the pressure which is existent in that part of the auxiliary air supply passage that is downstream of the closed position of said rectilinearly movable valve member so that the position of said second valve member relative to the co-operating valve seat is dependent upon the depression established within the auxiliary air supply passage downstream of the closed position of said rectilinearly movable valve member as well as upon the depression which is established within that part of the auxiliary air supply passage with which the fuel metering orifice communicates and the biassing load which acts to urge said second valve member towards said valve seat. 
     
     
       12. A cold starting device according to claim 11, wherein the relationship between said biassing load and the dimensions of said second valve member, said valve seat and said movable wall is such that the depression established by engine suction within that part of the auxiliary air supply passage with which the fuel metering orifice communicates is a function of the inverse of the depression established within the auxiliary air supply passage downstream of the closed position of the rectilinearly movable valve member. 
     
     
       13. A cold starting device according to claim 11 wherein said second valve is guided for rectilinear movement towards and away from said co-operating valve seat, is displaced laterally with respect to said rectilinearly movable valve member and is fixed to one end of a plunger which is engaged for sliding movement within a bore in a body within which said auxiliary air supply passage is defined, the other end of said plunger comprising said movable wall surface. 
     
     
       14. A cold starting device according to claim 13, wherein said second biassing means comprise a coil spring, said bore is the bore of a tubular member housed in a bore in said body, and the coil spring reacts against said tubular member, the location of said tubular member within said body being adjustable axially in order to alter the biassing load exerted by said coil spring upon said other valve member. 
     
     
       15. A cold starting device according to claim 14, wherein said tubular member is screwed into the bore in said body within which it is housed so that it can be rotated for axial adjustment relative to the body. 
     
     
       16. A cold starting device according to claim 10, wherein said first biasing means comprises a coil spring which has a diameter greater than the diameter of said orifice with which the plug valve member co-operates and greater than the diameter of the valve seat with which said annular valve member co-operates and the annular valve member has radially outwardly projecting spokes which are engaged by said coil spring. 
     
     
       17. A cold starting device according to claim 8 wherein the beam is adapted to engage said second valve member and hold said second valve member displaced from its associated valve seat when the engine has attained its normal operating temperature. 
     
     
       18. A cold starting device for an internal combustion engine, the cold starting device comprising an auxiliary air supply passage; one end of the auxiliary air supply passage being for connection to the inlet manifold of an internal combustion engine so that air can be drawn through the auxiliary air supply passage by the action of engine suction when the device is installed on an internal combustion engine; throttling means for throttling such air flow through the auxiliary air supply passage; means for varying the effective cross-sectional area of a part of said auxiliary air supply passage upstream of said throttling means so as to control the depression established within the auxiliary air supply passage between said passage part and said throttling means, yieldable biassing means for biassing said area varying means to minimise the effective cross-sectional area of said passage part, said yieldable biassing means acting in opposition to the effect upon said area varying means of a depression established within the auxiliary air supply passage between said passage part and said throttling means which tends to increase the effective area of said passage part; and a fuel control valve which is operable to allow fuel to be drawn from a fuel supply system into the auxiliary air supply passage between said passage part and said throttling means by the action of a depression which is established in the auxiliary air supply passage between said passage part and said throttling means, wherein the improvement comprises a movable wall having a surface which is exposed to the pressure which is existent in the auxiliary air supply passage downstream of said throttling means, the movable wall being coupled to the area varying means by thrust transmitting means so that the thrust due to the action on said movable wall surface of the pressure in said auxiliary air supply passage downstream of said throttling means is transmitted to said area varying means to act thereon in opposition to the action of said yieldable biassing means, the arrangement being such that the effective cross-sectional area of said passage part is dependent upon the depression established with the auxiliary air supply passage downstream of said throttling means by engine suction as well as upon the depression which is established within the auxiliary air supply passage between said passage part and the throttling means, and upon the biassing load exerted by yieldable biassing means. 
     
     
       19. A cold starting device according to claim 18, wherein the throttling means comprise a throttle valve having a throttle valve member and biassing means which bias said throttle valve member into an open position at least when the cold starting device is in use, the throttle valve member being arranged so as to tend to be moved by engine suction into a closed position in which it minimises the flow of air past it to the engine. 
     
     
       20. A cold starting device according to claim 19, including guide means which guide said throttle valve memeber for rectilinear movement within said auxiliary air supply passage between said open and closed positions. 
     
     
       21. A cold starting device according to claim 19, including a thermostatically controlled movable stop for limiting movement of said valve member towards said closed position, the position of said stop being related to engine temperature so that the permitted movement of said valve member is minimised by said stop when the engine is cold and is increased as the engine warms up towards normal operating temperature whereby movement of said valve member to said closed position is permitted. 
     
     
       22. A cold starting device according to claim 18, wherein said area varying means comprise a valve member, and a co-operating valve seat positioned within said auxiliary air supply passage upstream of said throttling means, said yieldable biassing means urging said valve member into engagement with said valve seat. 
     
     
       23. A cold starting device according to claim 22, wherein said yieldable biassing means comprise a coil spring. 
     
     
       24. A cold starting device according to claim 22, wherein said passage part is displaced laterally with respect to said throttling means and said valve member is fixed to one end of a plunger which is engaged for sliding movement within a bore in a body within which said auxiliary air supply passage is defined, the other end of said plunger comprising said movable wall surface.